I assume you mean you have an external DVD/CD drive. It sounds like you unplugged the drive while the program was still trying to access the DVD. There are two possibilities. 1) try pressing and holding the Command & Option keys and then pressing the ESC key. This will bring up the Force Quit menu. One of the items in that menu may indicate that it is not responding. If so, select that item and click on the Force Quit button. If that works (the image on the screen goes away and you can see the desktop again) click on the red close window button on the menu and resume using your computer. If it doesn’t work you’ll have to use option 2. 2) Hold the power button (the button above the Delete key) for about 10 seconds. This force quits the entire computer which should always be used only when nothing else works. The computer will shut down and then you can restart it. When I force quit my computer I generally immediately run the Disk Utility program and Verify the disk (not verify permissions). One of the most likely times for disk corruption to occur is when the computer is force.